I've heard there is a little device which allows the rear window on a C4 to be open a few inches but is still effectively locked in place. Allows thru air flow. Has any one used one - your thoughts - and has any one got one for sale or even for loan so I can test for myself. The above is the vain Rantings of a person who really wants Air Con but can't get motivated to fix it up. Any help or advice much appreciated.